Solid state imagers generally include an array of photosensors which receive the light from the image being sensed and convert the light to electrons, and means for transferring the electrons generated in the photosensor to an output circuit of the imager. For example, one type of imager includes an array of Schottkybarrier detectors arranged in an array of rows and columns along the surface of a substrate of single crystalline silicon as the photosensors. Along each column of the detectors is a CCD shift register which receives the electrons from the detectors in the column and transfers the electrons to an output CCD register. Such an imager is shown and described in an article by W. F. Kosonocky et al. entitled "Design and Performance of 64.times.128 element PtSi Schottky-barrier Infrared Charge-coupled Device (IRCCD) Focal Plane Array", published in SPIE, Volume 344, Infrared Sensor Technology (1982), pp. 66-77. In such an imager, only the light which impinges on the detectors is converted to electrons, whereas the light impinging on the CCDs between the columns of detectors is lost. This reduces the efficiency of the imager.
One technique which has been developed to improve the amount of light which reaches the detectors is to provide means for directing the light away from the CCDs towards the detectors. The light directing means has been a lenticular array of cylindrical lenses formed on a transparent substrate and mounted on the surface of the imager substrate with each cylindrical lens being aligned with and extending along a column of detectors. Such an arrangement is shown in the article of H. G. Erhardt et al., entitled "Silicon Cylindrical Lens Arrays For Improved Photoresponse in Focal Plane Arrays", SPIE, Vol. 501, State-of-the-Art Imaging Arrays and Their Applications, (1984), pp. 165-172. Thus, light passing first through the lenses of the lenticular array is directed away from the CCDs and toward the detectors to increase the efficiency of the imager. A problem with this type of lenticular array is the difficulty in making the lenticular array and mounting it on the imager with the lenses aligned with the detectors. It has also been suggested to form the lenses of the lenticular array directly on the substrate of the imager with the imager being formed along one surface of the substrate and the lenses along the other surface of the substrate. However, this also raises a number of problems since no matter whether the imager or the lens is made first, forming the other can adversely affect the one made first.